The present invention relates to a new and distinct cultivar of Hydrangea macrophylla, a member of the Hydrangeaceae family, hereinafter referred to as ‘HYMMAD I’. This cultivar is grown primarily as an ornamental for landscape use and for use as a potted plant, fresh cut and dried flowers. The cultivar originated from open-pollination of Hydrangea macrophylla ‘White Wave’ (non-patented), the pollen donor being unknown. It was selected at the University of Georgia, Athens, Ga. in 2002, from the progeny seedlings of this open pollination by continued evaluation for pure white mophead flowers unaffected by the absence or presence of aluminum (Al), increased resistance to mildew, and improved leaf and flower characteristics.
‘HYMMAD I’ is distinguished from its female parent ‘White Wave’ by its pure white, mophead inflorescence that does not turn pink or blue in the absence or presence, respectively, of Al. The inflorescence matures a virbrant lime green and maintains the color when utilized as dried flowers. ‘HYMMAD I’ has lustrous, more leathery, bullate, darker green leaves than ‘White Wave’. ‘HYMMAD I’ had no mildew in late summer, whereas in side-by-side comparisons, ‘White Wave’ showed 25% infection by mildew. The mophead inflorescence of ‘HYMMAD I’ is dense, domed-shaped, and the sepals completely cover the fertile flowers whereas the lacecap inflorescence of ‘White Wave’ has a row of sterile florets around the periphery and fertile flowers in the center.
‘HYMMAD I’ has better cold resistance than other white mopheads such as ‘Regula’ (‘White Bouquet’) (unpatented), ‘Schwan’ (unpatented) or ‘Soeur Thérèsa’ (unpatented) and the sterile florets do not have the pink or blue eye of ‘Mme Emile Mouillère’ (unpatented).